Semiconductor device including polysilicon resistor and metal gate resistor and methods of fabricating thereof

A described method includes providing a semiconductor substrate. A first gate structure is formed on the semiconductor substrate and a sacrificial gate structure formed adjacent the first gate structure. The sacrificial gate structure may be used to form a metal gate structure using a replacement gate methodology. A dielectric layer is formed overlying the first gate structure and the sacrificial gate structure. The dielectric layer has a first thickness above a top surface of the first gate structure and a second thickness, less than the first thickness, above a top surface of the sacrificial gate structure. (See, e.g., FIGS. 5, 15, 26). Thus, a subsequent planarization process of the dielectric layer may not contact the first gate structure.